1. The Field of the Invention
The present invention relates to novel apparatus and methods for the recovery and recycling of refrigerants used in common commercial devices, including household and automotive appliances. More particularly, the present invention is directed to a lightweight, on-site, portable system for the evacuation, filtering, storage, replacement, and/or recycling of refrigerants from appliances.
2. Technology Review
Refrigeration systems such as those used in automotive and home appliances and air conditioners require that the refrigerant used be relatively free of foreign matter such as oil, water, and air. Since these systems rely on pressure to keep the refrigerant compressed, it is vital that hermetic integrity be maintained.
If the refrigeration system breaks down, the refrigerant must be removed to facilitate the repair of the system. In the past, the refrigerant (a colorless, odorless, gas) was merely discharged into the atmosphere. This discharge only wasted the relatively expensive refrigerant, but as has been recently discovered, may also have contributed significantly to the breakdown of the ozone layer of the earth's atmosphere. Because fluorocarbons used in automotive and household appliances are environmentally hazardous, it is desirable to prevent their harmful release.
Recycling capabilities provide a financial benefit for technicians who filter and reuse refrigerant instead of replacing it with relatively costly new refrigerant. Containment and recycling might also prove to be economically beneficial to the technician who recovers the refrigerant from refrigeration units beyond repair.
Unfortunately, the environmental and economic advantages of recycling refrigerant must compete with the temptation of simply releasing the refrigerant into the atmosphere. In light of this conflict, any successful recovery or recycling system must provide repair personnel with a lightweight portable, easy to use apparatus that would encourage the recycling of the refrigerant, otherwise, the easier course of merely releasing the refrigerant into the atmosphere will be followed
While it is known to recover and recycle refrigerant as described in U.S. Pat. No. 3,232,070, these early systems only remove the refrigerant, filter and dry it, then condense the refrigerant for storage in an external holding tank. The system described in this reference lacks the capacity to reintroduce the refrigerant back into the appliance after repairs have been performed; moreover, it provides no design for cleaning the refrigerant before it enters the recovery apparatus. The result is that the recovery apparatus compressor pump is exposed to all of the contaminants that the refrigerant has accumulated, thereby shortening the life of the recovery compressor pump and preventing any recycling of the refrigerant.
Attempts to lessen the maintenance requirements by filtering the pressurized vapor before it passed through the compressor pump of the recovery unit led to another problem. To pass the volatile refrigerant through the newly developed filters required an increase in pressure. This increase in turn, required stronger filters. This ever increasing spiral eventually has led to the development of heavy armored filters. The increase in pressure required by the filters precipitated a concomitant increase in the wall thickness of the conduits used to transport the refrigerant. While these filters lengthened the life of the compressor pump, they added substantially to the weight of the recovery device, thereby making them difficult to transport.
Furthermore, because of the strength required to withstand the pressure and the need to be airtight, filters are often difficult to access. Cleaning these filters increases the maintenance needs of the refrigerant recovery device and service intervals are often difficult to determine owing to the variable amount of contaminant issuing from each disabled refrigeration unit.
Each possibly disabling malfunction of a refrigeration unit introduces differing amounts of impurities into the refrigerant. These impurities may rapidly build up to the point that the filter can no longer purify the gas or may become clogged. In the event that these filters become blocked, the requisite vacuum needed to draw materials through them will eventually overtax the pump, thereby damaging it or resulting in an explosion. These higher pressure systems expose technicians to the dangers of explosion and other risks such as eye and skin damage inherent with gases accidentally released under high pressure.
Further adding to the maintenance difficulties of these devices is the lack of any counting mechanism to remind technicians of the need to clean the filters and perform other maintenance chores. Several technicians may use the same refrigerant recovery device on jobs producing varying amounts of impurities to be filtered. This lack of ability to record usage, may lead to compressor failure due to clogging in the filters from lack of proper care and maintenance.
The weight of such recovery devices dictates that they be used mostly in commercial or industrial applications where a vehicle can be used to transport them to the appliance. Even so-called "portable" devices in use today weigh over 150 pounds and require permanent mounting to a two-wheel hand truck or dolly for transport, discouraging their use in apartments with stairs or in tight places.
The size of refrigerant recovery devices also discourages their use. Many of the refrigerant recovery devices transported by dolly or hand-truck, in addition to being very heavy are also unwieldy because of their size. It is difficult to maneuver a large device into the maintenance closets and back rooms that these refrigeration devices are often placed in. Additionally, refrigeration devices are often placed on roofs and in other locations requiring negotiation of tight turns and narrow stairways.
A further problem encountered by past devices as a result of the pressurized vapor has concerned the control of the flow throughout the recovery apparatus. Devices that vaporize refrigerant before reintroducing it to the repaired appliance require a separate routing of refrigerant to the vaporizer. This alternate route employs a plurality of valves to prevent back-flow and to control the flow of the refrigerant to the vaporizer. These valves have added to the complexity of refrigerant recovery systems and further discouraged the use of these devices for anything but large commercial operations. Indeed, the complexity may have actually led to mistakes further damaging the appliance to be repaired. The multiplicity of valves has also contributed to the high maintenance requirements of past devices and increased the danger of malfunction and possible injury to technicians.
A still further problem experienced by repair personnel has been the need to transport several devices to perform ancillary functions in the repair of refrigeration systems. As air, oil and other contaminants infiltrate a system, they form blockages that are not removed with the refrigerant. Accordingly, it is often necessary to use a separate device with the capacity to blow obstructions out of the system.
Still other devices often need to be transported to the repair site to monitor the system for leaks after repair and before the refrigerant is reintroduced. Repair personnel often need a separate device to evacuate the contaminated air in the system after repair. This practice subjects compressors to even further contact with contaminants and, as a result, shortens the maintenance interval and life of the compressor.
One significant current problem associated with reintroducing refrigerant into refrigeration systems concerns the use of heat-exchangers to vaporize the liquid refrigerant. Current systems utilize a joint condenser/evaporator unit that requires additional valves to reroute the refrigerant back through the system. The evaporator and attendant valves add to the weight and complexity of recovery devices, thereby discouraging their frequent use and increasing the need for frequent maintenance. The increased complexity added to refrigerant recovery devices by these valves also contributes to the chance for error and possible accident in the repair of appliances and in any use of the refrigerant recovery device.
After vaporization, the gaseous refrigerant is usually slowly bled back into the refrigeration device or pumped into the low pressure side of the refrigeration device's compressor. Both methods are time consuming because they both require the vaporization of the refrigerant before reintroduction into the refrigeration device. As the refrigerant is converted to gaseous form, it must be slowly reintroduced so as not to be compressed in the refrigeration unit and converted to liquid before entering the compressor of the refrigeration unit. Too much liquid introduced into the low pressure side of the refrigerant unit's compressor could damage the compressor.
Another problem involving the time consumed in refrigeration unit repairs concerns the down-time, or period during which the refrigeration unit is inoperable. Refrigeration units used in the food industries are vital to the preservation of large amounts of inventory and often to the very operation of the business. Ice cream stores and many restaurants must close for business if the refrigeration system is disabled for any length of time.
From the foregoing, it will be appreciated that what is needed in the art are novel, lightweight, portable, refrigerant recovery apparatus and methods embodied in a single device for recovering refrigerants in which the refrigerant can be readily and safely evacuated, filtered, stored, and then reintroduced back into the refrigeration appliance or recycled for further use.
Additionally, it would be an advancement in the art to provide novel, lightweight, portable, refrigerant recovery apparatus and methods with few valves and controls so simple that its ease of operation would encourage its use and thereby preserve the environment from the deleterious effects of released refrigerant.
It would be a further advancement in the art to provide novel, lightweight, portable refrigerant recovery apparatus and methods that could be contained in one unit that was small and light enough to be easily carried into crowded maintenance rooms and through narrow openings and stairways.
It would be a further advancement in the art to provide a novel, lightweight, portable refrigerant recovery apparatus and methods that functions as a leak sensor to test the efficacy of repairs or in analysis of possible defects before repairs are begun.
It would be a further advancement in the art to provide a novel, lightweight, portable refrigerant recovery apparatus and methods for evacuating contaminants remaining in a depressurized system prior to reintroduction of clean refrigerant.
It would be a further advancement in the art to provide a novel, lightweight, portable refrigerant recovery apparatus and methods with capacity to blow out obstructions in a blocked system.
It would be a further advancement in the art to provide a novel, lightweight, portable refrigerant recovery apparatus and methods which require little maintenance through the use of lubricated-for-life components and disposable filters.
It would be a further advancement in the art to provide a novel, lightweight, portable refrigerant recovery apparatus and methods which provided a counting mechanism to remind the user when the disposable filter needed to be replaced.
It would be a further advancement in the art to provide a novel, lightweight, portable refrigerant recovery apparatus and methods that could quickly reintroduce refrigerant into repaired refrigeration units in a liquid form to the high pressure side of the compressor foregoing any need for an evaporator and its attendant valves and the slow reintroduction of the refrigerant in gaseous form.
It would be an additional advancement in the art to provide a novel, lightweight, portable refrigerant recovery apparatus and methods that could be used as a temporary refrigeration unit for maintaining operation of a business while repairs are being performed on a disabled refrigeration unit.